We’ve seen many value stream maps (VSM) over the past 20 years, as it has become a common tool. In some companies it’s a first requirement before a lean effort begins.
In other companies, value stream maps are regarded as burdensome and irrelevant. And that's a shame.
VSMs that are completed with no 'what next' analysis (other than post-its on a craft paper display in a conference room) serve no purpose. And when employees aren't involved in leveraging the VSM they've created into a better future state for the company, they will groan and roll their eyes when asked to participate in other VSM workshops.
The level of detail that's included in a VSM – and the team’s ability to interpret ‘current state’ as represented by the map – can make it difficult to see which improvement efforts can yield the best results. In some companies just beginning (or restarting) their lean process, some improvements appear so obvious that a map may seem unnecessary.
However, leaders who highlight the 'quick wins' achieved in the VSM workshop will give their team a sense of accomplishment. They'll also help participants understand the link between the current state value stream map, and opportunities to improve the process.
How can we make creating a value stream map less burdensome and more relevant? We’ll first review the basic structure of a full VSM. Then we’ll talk about why the map must be build with the right level of detail. Finally, we’ll review how these steps come together in a future state plan.
Value Stream Mapping – the Process
Many companies dedicate key resources for a week or more to complete the mapping process, and then declare their effort complete. That’s missing the mark, because value stream maps are never meant to be stand alone documents. The VSM should be regarded — to use a football analogy — as akin to putting the game plan together. After a VSM is created, the team must execute the plan – blocking, tackling, running and passing in order to win the game. In other words, using what’s learned from creating the VSM to realize an ideal future state of the process. If activities aren’t following the plan, the coach will alter the plan in order to achieve a positive result. The VSM merely maps out what the current state is. Then, a plan (based on findings from creating the VSM) is created to improve the business.
The VSM provides the foundation for a plan that should look out no more than six months. The team should re-convene to update their value stream map by recording improvements and changing business conditions. The plan is then compiled for the next six months. Because the same team is revising the VSM within six-month timeframes, the process becomes less burdensome and more relevant. The VSM communicates the progress the lean initiatives have made.
How Much Detail to Include?
The level of detail is critical when developing a VSM. The old phrase rings true: “Too much detail – you can’t see the forest for the trees.” And of course the corollary is also true, “Too little detail – and you can’t see the trees for the forest.”
The VSM provides the foundation for a plan that should look out no more than six months.
What the VSM is meant to show are all the problems encountered in a process (or, where improvements may have the biggest benefit). After all, the seminal book that put VSM in the mainstream lean world is titled Learning to See by Rother and Shook.
Three points to keep in mind:
- See and understand the current situation and where the bottlenecks are.
- See impediments to flow illustrated by excess queues of material or documents.
- See impediments to flow illustrated by poor or incomplete data.
Your improvement goals should drive the level of detail you include in your VSM. For an enterprise-level VSM, teams focus on identifying opportunities to reduce overall lead time. Process steps and the supporting data should illustrate opportunities to reduce days and weeks of lead time. If your team is mapping a work-cell process, then process steps and tasks in seconds, and a discrete count of inventory is required. The VSM should show where the problems are. If these bottlenecks aren’t readily visible, and you have a lot of information, then you’re too detailed. If your entire value stream shows only two or three process blocks, then you will probably need to break things down a bit further.
What’s the rule of thumb developed by teams we’ve worked with? They express a process in 20 to 30 steps within the primary flow. It’s always easier to identify where the team needs to dig a little deeper than it is to consolidate process steps. It’s also helpful to perform a self-check as you build your map. This can help you identify bottlenecks in the process before collecting data. If the main process flow already speaks to you about problems, or ideas jump off the sheet at you, then you know you’re at the correct level of detail. The correct level of detail will also lessen the burden of data collection and map compilation.
Bringing It All Together
When process data is overlaid on the map, an imbalance of inventory or data will help you see the bottlenecks and where they’re created. Analyze the opportunities presented by the map. They may be revealed by excess inventory buildup, material flow knocked out of balance by extended cycle times, quality issues or information flow that enters the process at the wrong place. As you begin to identify improvement opportunities, it should become clearer where to focus. Then, target your improvement areas, assign a project manager for each area and prioritize a value stream plan that can help your organization quickly realize the largest process benefits.
Repeating the Process for Continuous Improvement
Building a current state value stream map is your organization’s logical first step, but it should never end there. If you’ve crafted it correctly, the VSM should challenge the current state of the process you want to improve. The VSM will help you create a value stream plan to improve the process. And, most important, it will help you execute the plan.
The value stream plan should be valid for no more than six months, at which time the future state map should be the current state map.
Validate your current data with time observations, inventory counts and up-to-date quality metrics. Then the process of creating a value stream plan and future state map for the next six months begins (again). Use your current state map to identify new improvement opportunities, update your value stream plan, and then create another future state map incorporating all the ideas from the updated plan. It is a great example of W. Edward Deming’s “Plan-Do-Check-Act” cycle.
The knowledge your organization gains in mapping a current-state VSM makes the time you invest to develop it—and to define your ideal future state process—well worthwhile.
Tom Voss is a senior consultant with Daniel Penn Associates. He has developed and implemented lean enterprise solutions for more than 15 years. Trained and mentored in lean concepts by the founders of Shingijitsu Company, Ltd., renowned experts of the Toyota Production System, Tom held engineering, operations and other positions at General Dynamics, United Technologies-Pratt & Whitney, JDS Uniphase and Franklin Products.